fix initialization order
Use shared counter only for initialization.

Fixes equality comparison for anonymous QML data layers (where nameId
is unspecified) needed to have more than one QML data layer displayed
at once.

CCBUG: 317719
Work around a crash when clearing annotations while creating a polygon.

The temporary placemark is connected to the tree model, simply deleting
it leads to a crash. Code needs refactoring.
Code style fixes
Publish numberOfItems property to QML.

BUG: 317815
Respect tile format specified in .dgml files during tile creation.

CCBUG: 317562
introduce MarbleView
introduce MarbleGLView
introcude GlLayerInterface
clear depth buffer between layer rendering
TextureLayer
PlacemarkLayer
introduce triangulation algorithm for polygons

* taken from http://www.crystalspace3d.org/svnroot/crystal/CS/trunk/{include/csgeom/triangulate.h, libs/csgeom/triangulate.cpp}.
GeometryLayer
introduce GeoGraphicsScene::GlTile and use glDrawElements
adapt PlacemarkLayout
use shaders
GLRenderer